Why not? said:
Please excuse the hijack, Super Scout. Maybe Rick will start a new thread on this.
There's not much to it.
You heat treat WW cast bullets in the oven. I believe I have posted heat treatment tables here several times before, but they are a ##### to configure right in appearance. Immediately after quenching i.e. within a few hours, size/gascheck and lube. With a bullet that has a big flat meplate, I think you are probably good to go just as you are; they won't deform much (depending on velocity at impact), but they'll do a good job anyways.
If you want to soften up the noses somewhat to make them more likely to expand, stand your tempered bullets in ice water up until you are about a third of the way into the ogive. Then run a butane torch over the nose until they are just below slump temperature and then allow to cool. It's a bit of a trial and error thing - you can heat a couple until the noses slump while timing it, or look for the change in appearance.
What you will end up with is a bullet that has the original BHN in the base and the shank where it has to deal with the working pressure of the load, and a nose that is much softer and therefore deforms much more easily.
This is not my idea; it is a well known technique among the cast bullet affectionados. I'll post those tables once again, but I am going to put zero effort into formatting them yet again, so you will have to figure out the rows and columns yourself:
Common BHN measurements:
Pure lead 5 BHN
Wheel weights 8-13 BHN, composition varies
Lead/linotype 15 BHN, half and half
Linotype 22 BHN
40-1 Lead-tin 8.5 BHN
30-1 Lead-tin 9 BHN
20-1 Lead-tin 10 BHN
16-1 Lead-tin 11 BHN
10-1 Lead-tin 11.5 BHN
Lyman No. 2 15 BHN
Heat treated 25-35 BHN, varies with heat treat and age
Wheelweights
After 6 weeks, air cooled bullets will reach maximum hardness.
This hardness can be further increased by heat treating.
HEAT TREATING WHEELWEIGHTS
Heat treating wheel weight alloy is both controllable and predictable ie: It is possible to heat treat wheel weight bullets and predict the final hardness to be achieved.
Hardness does not increase until the quench temp (after a ½ hr heat soak) reaches 420 deg. F. as measured with a digital thermometer shaded from any direct radiant heat.
Temperature vs. Resulting Hardness
410 12 BHN
420 15 BHN
430 17 BHN
440 23 BHN
450 29 BHN
Conclusions:
Exceeding 450 did not cause any significant increase in hardness.
460 deg was very close (read that too close) to the plastic deformation stage of the alloy
OPTIMAL HARDNESS FOR OPERATING PRESSURE OF LOAD
Tensile strength of lead/lead alloys = BHN x 480
Best bullet performance is usually at pressures between 3 and 4 times
Tensile strength.
ALLOY BHN TENSILE STRENGH (PSI) TIMES 3 GIVES
MIN. CHAMBER PRESSURE (PSI) TIMES 4 GIVES
MAX. CHAMBER PRESSURE (PSI)
PURE LEAD 5 5(480)=2400 7,200 9,600
1-20 Pb/Sn 10 10(480)=4800 14,400 19,200
WHEEL WEIGHTS 12 12(480)=5760 17,280 22,040
LYMAN #2 15 15(480)=7200 21,600 28,800
LINOTYPE 22 22(480)=10560 31,680 42,240
HEAT TREATED WHEEL WEIGHTS 30 30(480)=14400 43,200 57,600
VELOCITY REQUIRED TO EXPAND OR DEFORM VARIOUS HARDNESSES
BHN MINIMUM TERMINAL VELOCITY HOLLOW POINTS*
5 (Pure lead) 1200 fps. 700 fps.
8 1300 fps. 800 fps.
10 1400 fps. 900 fps.
14-15 1500 fps. NR
18 1900 fps. NR
20 2200 fps. NR
30-35 2400 fps. NR
NR - Not recommended for game shooting because of extreme destructiveness. Good for varminting, though.
* - Hollow point size and bullet nose shape affect required terminal velocity greatly, so these can only be considered approximations. Hollow points are best used with pure lead or tin-lead alloys as even small amounts of antimony cause bullet break-up. If antimony alloys are used, do not exceed 1 ½ % antimony or 10 BHN.
